Improved machine for making twist-drills



. UNITED STATES MME arreter OFFICE.

AlllntlflT R. ARNOLD, OF NEVARK, NE\V JE tSEY, ASSIGNOR TO TUE MAN- HATTAN FIRE ARMS COMPANY, OF SAME PLACE.

IMPROVED MACHINE FOR MAKING TWIST-DRILLS.

Specification forming part of Letters Patent No. 44,037, dated August 30, 18H1.

To all whom, t may concern:

Be it known that I, ANDREW R. ARNOLD,

of Newark, in the State of New Jersey, have Fig. 2, in the plane of the axis of the man drei; Fig. 4, a section at y y of Fig. 2, in the plane of the axis of one of the burr-cutters, to exhibit the arrangement of the gearing for driving the burr-cutters; Fig. 5, a top View of the modification for finishing the grooves of twist-drills; Fig. 6, a vertical section in the plane of 011e of the cutters; Figs. T and S, side elevation and end view of a twist-drill as grooved by burreutters, and Fig. 9 au end '.view of such a cutter when finished Fig. 10,

an end view of Fig. 5.

The object of my invention is to cut or finish the two grooves which form what is termed a twist-drill7 at vone and the same operation by two cutters acting simultaneously on opposite sides of the blank, that the two may counteract each other, and thereby avoid all tendency to spring the blank.

In the accompanying drawings, a represents a 4suitable frame, and b the blank or cylindrical rod of steel which is being formed or cut. The lower end of this blank is inserted in a central socket at the upper end of a cylindrical mandrel, c, which is fitted to turn and slide longitudinally in suitable boxes in the two cross-bars d and e of the frame, and it also slides longitudinally in the eye of a cog-wheel,.f, to which it is feathered so as to beturned hyit.` A slow rotary motion is l:imparted to the mandrel c by a worm, g, on

the horizontal driving-shaft h, which carries a cone-pulley, t', to receive a band from some motor. The worm y drives a worm-wheehj, at the lower end of a vertical shaft, 7c, which carries a pinion, l, and this pinion, bythe train of wheels and4 pinion m n o, drives the wheelf on the mandrel c. ln this way a slow rotary motion is given to the mandrel and the blank b which it carries, which rotary motion l can he increased or diminished at pleasure by the conevpulley.

'Vhile the mandrel is rotated, as above described, it is gradually lifted by a regular motion derived from the same source as the rotary motion.

The norm-wheelj at the lower end of the vertical shaft k drives a cog-wheel, p, ou the lower end of a shaft, q, and the upper end of this shaft is threaded and fitted to the lower end of the mandrel c, which is made hollow and threaded for that purpose.

rlhe cog-wheel and pinion n o, before described, arc mounted and turn on a stud projecting from a bracket, r, attached to the frame by a screw-bolt passing through an elongated slot, or otherwise connected to admit of adjustment, so that they can be taken off and others of different size substituted to vary 1he relative speed of the rotary and longitudinal motions of the mandrel c, and thereby admit of making the twist to be cut of any desired pitch.

The operation of cutting the twist on the blank is performed while the mandrel is rising, and at the end of -this upward motion tl;e worm g on the driving-shaft is thrown out of gear with the worm-wheel j by a cam, s, on th mandrel, which then pushes aslide, t, on the under side of the crosslbar d of the frame. One end of the driving or worm shaft h is mounted in the lower arm of a lever, u, which turns on a fulcrum-pin, c. The upper arm of this lever has sufficient spring to be heldin place by avshoulder or catch on the frame while the worm gis in gear; but when the slide t is pushed out by the cam s it disengages the upper arm of the lever u, and the lower arm is then forcedoutward by a spring, w, to .throw the yworm out of gear. After this disengagement of the worm the mandrel can be run down rapidly by a crank-handle, a', on a short horizontal shaft, b', which communicates motion by the bevel cog-wheels c' c tothe vertical shaft k. To the top of the crossbar d or cap ofthe main frame is secured by screws or other suitable means an auxiliary frame., d', on the top of which are mounted two pupl pets, vc c, which slide horizontally in parallel ways. In each puppet is mounted an inclined arbor or spindle, j", which carries at its lower end aburr-cutter, g the cutting-edge of which f are mounted are attached to the'puppets by screw-bolts passing through elongatedV slots. In this way the arbors can be set at any desired in'xlination. Each arborf carries abevel cog-wheel, h', at its upper end, which meshes into the cogs of another bevel cog-wheel, i', that turns on a studpin, j. The opposite face of the bevel-wheel i is a rim, 7c', with cogs on its inner periphery, which engage the cogs of two pinions, Z l', that turn on stud pins arranged on opposite sides of the axis of the bevel-wheel, and which are attached to a plate, m', on the stud-pin j, on which the bevelwheel i, turns. The pulley fn', by which the arbors are driven by a belt from some motor, is mounted to turn on the Studpinj, and on its inner face it carries a pinion, o', which drives the two pinions Z l', and these in turn drive the bevel cog-wheel i', which is cogged'on its inner periphery, as at k', and this bevel-wheel drives the arbor. The inner face of the pulley n', which carries the pinion o', may be made of eLilarged diameter, with a rim, p', extending over the rim of the beveled wheel, and the o itside of this rim is in the form of and can be used as a pulley when desired.

The burr-cutters are arranged and operate on opposite sides of the blank, each cutting one groove, and in this way I am enablednot only to cut the twist in one-half the time heretofore required, but to avoid all tendency to spring the blank-a difficulty heretofore expeiienced, and which cannot take place in this arrangement, as the cutters in their action counteract each other. The puppets which c irry the two burr-cutters, as before stated,

slide in parallel ways, and each is set tothe di pth of cut to be made by an adjustable gage, a. Before starting the machine each puppet i; pushed against its gage.

The grooves'forming the twist-drill are: of the greatest depth at the cutting end of the drill, and ol' gradually less depth toward the shank, as represented by dotted lines in the sepanlite Fig. 11, represen ting asection of such a dril On account of the gradually-reduced depth of the grooves of the drill, the burr-cuttersare gradually moved from thie'axis of the blank as it rises during the operation. To effectithis i motion of the cutters, there is a collar, r', on

the upper end of the mandrel c, and which,.

for adjustment, can be shifted and fastened by a vtemper-screw at any desiredl distancel from the upper end ofthe mandrel. Ay lever,

elevated as the mandrel rises. The opposite end of the lever is slotted and embraces an adjustable pin, a', on the lower end of a sliding cogged rack, vf, which engages the cogs of a pinion, a", on the end of a screwshaft, no', mounted on the top ofthe auxiliary frame d', and the thread on this shaft engages and slides the puppet, so that as the mandel with its collar r rises the lever depresses the cogged rack, which turns the screw-shaft, and this in turn slides the puppet with the burrcutter gradually from the axis of the blank. When the operation is completed, the rack is disengaged from the pinion on the screw-shaft, to admit of moving back the puppet to its place of starting against the gage q', by a crank-handle, y. This disengagement ofthe rack is effected by turning a. button, z', situated behind the rack.

To adjust' the parts to increase ordecrease theran ge of motion, the fulcrum-pinon which the lever s vibrates is adjustable in'a slot of the'bracket from which it projects, so that it can beset near to or farther fromthat end of the lever which bears on the collar; andin like manner the pin which is acted upon by the other arm of the lever is fitted and secured in a slot in the lower endiot1 thecogged rack. The otherpnppet is provided withv a like arrangement. 4

The parts being adjusted, the mandrel let down, a blank inserted, and the puppetsY of the'burr-cutters setup against their gages and the machine started, the mandrelwill'rise gradually to present thepointof tlieblank to the burr-cutters, which gradually cut the two grooves as the'mandrel continues to raise and` turn the blank,\botli motions being'so timed and proportioned'as to give the desired twist' to `the two grooves, and asthesc motions proceed the two' burr-cutters are gradually movedi'rom` the axis of the blank to reduce tlie'depth of cut, and in this way and-atY one operation the two grooves, to forma' twistdrill, are cutV simultaneously and without strain on the rodjof'stcel.

The cutting-,edges formed on'theendiof the twist-drill, by reason ofthe form 'ofthe grooves made. by the burreutters, will be curved, and

yas it'is desirable to have such' cuttingedges straight, Isubject the formed drill toa" second operation in the same machine, substituting'whatzare known as' cherry-cutters for the'burr-cutters labove described.

The mode oflapplying the cherry-cutters is represented in Figs;5 and 6. Forconvenience I take 'o the auxiliary frame abovede'scrixbed from the main frame and substitute there*- for the auxiliary frame' a2, which isin all essential' respectsI like it; The puppets" b2 b? slide in parallel ways on' theA top,`.and thesev are adjusted by screw-shaftscg c2 with crank-handles. The 'cherry-cutters" d2 d are semi-spherical at their front'ends andconical at their rear ends. They are securedv in the front ends of two aib'ors e2 c2, each 'carryin gva cone of pulleys, f 2, to receive the drivin g-belt.

Each mandrel is fitted to turn in a sleeve, g2,

v the outer periphery of which is threaded and tapped in the puppet, and the outer end of the sleeve is provided with a cog-wheel, h2, which engages and is turned by a cogged rack, i2, connected with the lever jz, operated by the collar r on the mandrel c, as already described, for cutting the grooves of gradually less depth with the burr-cutters.

By the arrangement last described the two grooves cut by the burr-cutters are enlarged, the. semispherical end of the cherrycutters iinishing the bottom of the two grooves which form the twist-drill, and the conical part of the cutters forming the sides of the grooves, so that when the end of the drill is ground off' to a bevel the cuttingedges thereby formed will be straight.

I have thus described and represented the mode of construction which I have tried with success, and which I prefer; but I do not wish to be understood as limiting my claim of invention to such mode of application, as it may be varied by the substitution of mechanical equivalents having the same mode of operato i.

What I claim as my invention, and desire to secure by Letters Patent, is

l. The arrangement of the two rotating cutters, whether for cutting or finishing the two grooves, and acting simultaneously on opposite sides of the blank, substantially as described, in combination with the mandrel fr r carrying the blank, and having` a simultaneous longitudinal and rotary motion, substantially as described, whereby I am enabled to cut or tinish both grooves at the same time and of the required pitch, without tendency to spring .the blank, as set forth.

2. Moving the cutter or cutters gradually from the axis of the blank, to make thegroove or grooves of gradually less depth, by means of the sliding puppet (or puppets) in Which the cutter (or cutters) is mounted, the sliding mandrel with acollar, or the equivalent thereof, and the mechanism, or the equivalentthereof', by which the rising of the mandrel communicates the required motion to the puppet for cutting the grooves of' gradually less depth, as set forth.

3. The arrangement ot' gearing for communicating rotary motion from the shaft k to the wheel o, in which the mandrel c slides, and to which it is feathered so as to be turned thereby, in combination with the rotating screw-shaft q, which receives motion from the shaft 7c, and which imparts the required longitudinal m0- tion to the mandrel c, substantially as and for the purpose specied.

4. The combination and arrangement of gearing herein described for transmitting mo tion from the driving-pulleys n to the burrcutters g.

ANDREV R. ARNOLD.

Witnesses:

WM. H. ISisHor, A. Dn LACY. 

